Recently, flat-panel display devices have been greatly developed and, specifically, liquid crystal display devices have been noticed with respect to features such as lightness, slimness and low power consumption. In particular, a structure using a lateral electric field (including a fringe field) such as fringe field switching (FFS) mode, of active-matrix liquid crystal display devices comprising switching elements built in respective pixels, has been noticed. In such a liquid crystal display device of the lateral electric field mode, pixel electrodes and common electrode are formed on an array substrate, and liquid crystal molecules are switched by the lateral electric field substantially parallel to a main surface of the array substrate.